Device and Method for Controlled Motion of a Tool

ABSTRACT

The present invention relates to devices and methods for controlled motion of a tool. In one embodiment, the device can support a tool needed to perform an activity requiring a highly-precise, stable motion, while also accommodating a person&#39;s hand for the purposes of moving the tool. In another embodiment, the device of the present invention allows for rotational motion of a tool independently of the directive motion of the tool. In yet another embodiment, the present invention relates to the design of a force transducer useful in a cooperative robot. The device and methods of the present invention are particularly useful for microsurgery or other tasks that are typically performed using cooperative robotics.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 61/784,972 filed Mar. 14, 2013, and U.S. ProvisionalPatent Application No. 61/802,149 filed Mar. 15, 2013, which areincorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

Cooperative or collaborative robot devices, i.e., cobots, are devicesthat generally require a human operator to interact physically with therobot to perform a task, such as manipulating a tool, rather than therobot acting relatively autonomously based on little or no humaninstruction. Such cobots are particularly useful for performing tasksrequiring a level of precision that is difficult or impossible for ahuman to attain without assistance. For example, microsurgery, i.e.,surgery requiring manipulation on a sub-millimeter scale, is a task thatis particularly well-suited for the use of a cobot device.

Cobot devices and methods currently available in the art include thecobots described by Colgate and Peshkin (U.S. Pat. No. 5,952,796); themethod of cooperative control of a surgical tool described by Taylor etal. (US Patent App. Pub. No. 2013/0296884 and US Patent App. Pub. No.2013/0304258); the steady hand micromanipulation robot described by Oldsand Taylor (US Patent App. Pub. No. 2013/0131867); and the DA VINCI™surgical system by Intuitive Surgical Operations (see e.g. U.S. Pat.Nos. 6,902,560, 7,398,707, 7,914,522, and 8,528,440).

However, currently available devices for cooperative robot control canbe extremely expensive. Further, these devices often provide a highdegree of freedom for the tool that is being controlled, at the expenseof providing optimal precision and stability.

Thus, there is a continuing need in the art for devices and methods thatcan provide stable, high-precision controlled motion of a tool. Thepresent invention addresses this continuing need in the art.

SUMMARY OF INVENTION

The present invention relates to devices and methods for controlledmotion of a tool. In one embodiment, the device of the present inventionis a device for reducing tremor in a tool, comprising: a grip suitablefor engaging a tool, a sensor assembly connected to the grip, amicromanipulator associated with the grip, and at least onemicroprocessor operatively connected with the micromanipulator and thesensor assembly, wherein when a force is applied to the grip, the sensorassembly sends an input signal to the microprocessor indicative of theapplied force, and upon receiving the input signal, the microprocessorsends an output signal to the micromanipulator directing themicromanipulator to apply movement to the grip in the direction of theapplied force. In one embodiment, the micromanipulator is associatedwith the grip via the sensor assembly. In one embodiment, the outputsignal is produced by applying a gain to the input signal.

In one embodiment, the device further comprises a tool. In oneembodiment, the tool is selected from the group consisting of a forceps,scalpel, and drill.

In various embodiments, the device can comprise a base. In oneembodiment, an end of the sensor assembly is connected to the base. Inanother embodiment, the base comprises the micromanipulator. In anotherembodiment, the base comprises a mechanism for securing the base to asurface.

In various embodiments, the grip of the device of the present inventioncan comprise other components. In one embodiment, the grip comprises atool holder. In one embodiment, when a tool is connected to the toolholder, the tool holder allows a first portion of the tool to be rotatedalong an axis while a second portion of the tool is maintained in aconstant position. In another embodiment, when a tool is connected tothe tool holder, the tool holder selectively prevents rotational motionof the tool. In yet another embodiment, the tool holder can be rotatedwithout transferring significant applied force to the sensor assembly.In one embodiment, the grip is connected to the sensor assembly via abracket. In another embodiment, the grip is connected to the sensorassembly via a rotational housing. In another embodiment, the gripcomprises a fixed point mechanism, so that as the tool is rotated, apoint near the tool tip remains approximately stationary relative to themounting point of the grip.

In one embodiment, the device of the present invention is a forcetransducer, i.e., a sensor subassembly, for a controlled-motion devicecomprising: a first support, a sensor connected to the first support, asecond support, and a bridge connected to the second support, whereinthe bridge further comprises a magnet, wherein the first support isconnected to the second support via one or more sheets so that the firstsupport and second support are separated by a gap, wherein the magnet ispositioned near the sensor when the first support and second support areconnected via the one or more sheets, and wherein the sensor can sense achange in position between the first support and second support when aforce is applied to either the first support or the second support via achange in position of the magnet. In one embodiment, the sensor sensesthe vector component of the force that is perpendicular to the one ormore sheets. In another embodiment, the change in position between thefirst support and the second support from the force is due to flexion ofthe one or more sheets.

In various embodiments, the sensor of the device of the presentinvention can be any sensor known in the art. In one embodiment, thesensor is selected from the group consisting of an optical, magnetic,inductive, and capacitive sensor.

In one embodiment, the sensor of the device of the present invention isa sensor assembly for sensing forces along three axes, comprising: afirst force transducer, wherein said first force transducer can detect aforce along an X-axis, a second force transducer, wherein the firstsupport of said second force transducer is the second support of saidfirst force transducer, and wherein said second force transducer candetect a force along a Y-axis, and a third force transducer, wherein thefirst support of said third force transducer is the second support ofsaid second force transducer, and wherein said third force transducercan detect a force along a Z-axis. In one embodiment, the first, second,and/or third force transducers are the force transducers, i.e., sensorsubassemblies, of the present invention described herein.

In one embodiment, the method of the present invention is a method forstabilizing the motion of a tool, comprising the steps of: sensing aforce applied to a grip via a sensor assembly, wherein the grip isassociated with a tool, sending an input signal to a microprocessorindicative of the applied force, sending an output signal from themicroprocessor to a micromanipulator, wherein the output signal directsthe micromanipulator to apply movement to the grip in the direction ofthe applied force. In one embodiment, the tool associated with the gripis selected from the group consisting of a forceps, scalpel, needle, anddrill. In another embodiment, the output signal is produced by applyinga gain to the input signal. In yet another embodiment, themicromanipulator applies movement to the grip via the sensor assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description of various embodiments of theinvention will be better understood when read in conjunction with theappended drawings. It should be understood, however, that the inventionis not limited to the precise arrangements and instrumentalities of theembodiments shown in the drawings.

FIG. 1 is a schematic diagram of an exemplary embodiment of the deviceand the present invention and how it relates to an operator.

FIG. 2 is a schematic diagram of an exemplary embodiment of sensorassembly of the device of the present invention.

FIG. 3, comprising FIGS. 3A and 3B, is a set of schematic diagrams ofexemplary embodiments of a sensor subassembly, i.e., a force transducer,of the present invention.

FIG. 4 is a flow chart representing the control system of an exemplaryembodiment of the present invention.

FIG. 5 is a schematic diagram of an exemplary embodiment of a toolholder and grip of the present invention with a rotational arm.

FIG. 6, comprising FIGS. 6A through 6C, is a series of schematicdiagrams of an exemplary embodiment of a tool holder and grip in variousstates of rotation.

FIG. 7 is a schematic diagram of the cross-section of a portion of arotational tool holder and grip of the present invention.

FIG. 8, comprising FIGS. 8A and 8B, is a series of schematic diagramsshowing an exemplary embodiment of a grip of the present invention.

FIG. 9 is another schematic diagram of an exemplary embodiment of a gripof the present invention.

FIG. 10 is a schematic diagram of an exemplary embodiment of a toolholder.

FIG. 11 is a schematic diagram of an exemplary embodiment of a toolholder and grip of the present invention.

DETAILED DESCRIPTION

It is to be understood that the figures and descriptions of the presentinvention have been simplified to illustrate elements that are relevantfor a clear understanding of the present invention, while eliminating,for the purpose of clarity, many other elements found in the field ofelectromechanical devices, robotics, and the like. Those of ordinaryskill in the art may recognize that other elements and/or steps aredesirable and/or required in implementing the present invention.However, because such elements and steps are well known in the art, andbecause they do not facilitate a better understanding of the presentinvention, a discussion of such elements and steps is not providedherein. The disclosure herein is directed to all such variations andmodifications to such elements and methods known to those skilled in theart.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the present invention, the preferred methodsand materials are described.

As used herein, each of the following terms has the meaning associatedwith it in this section.

The articles “a” and “an” are used herein to refer to one or to morethan one (i.e., to at least one) of the grammatical object of thearticle. By way of example, “an element” means one element or more thanone element.

“About” as used herein when referring to a measurable value such as anamount, a temporal duration, and the like, is meant to encompassvariations of ±20%, ±10%, ±5%, ±1%, and ±0.1% from the specified value,as such variations are appropriate.

Throughout this disclosure, various aspects of the invention can bepresented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, 6 and any wholeand partial increments therebetween. This applies regardless of thebreadth of the range.

DESCRIPTION

The present invention relates to devices and methods for stabilizing aperson's hand while performing an activity, especially an activityrequiring highly precise, stable motion. The device can support a toolneeded to perform the activity while also accommodating a person's handfor the purposes of moving the tool. Alternatively, the device canaccommodate and/or support a person's hand while the person holds such atool.

In one aspect, the device comprises a sensor assembly that issufficiently rigid to provide stabilizing support for the operator'sfingers and/or hand. When an operator supplies directive force to asensor assembly via the operator's fingers and/or hand, forcetransducers associated with the sensor assembly communicate the measuredforces to a controller. The controller can combine the force informationwith other information, such as a gain setting, and apply a variety ofalgorithms to determine a motion response. The controller can then sendsignals to a driving system such as a 3-axis micromanipulator, which canmove the sensor assembly, along with anything connected or in contactwith the sensor assembly, including the operator's hand and/or any toolheld by the operator or connected to the sensor assembly. In this way,the operator can guide the motion of his hand and tool while the handand tool are being stabilized by the device.

In various embodiments, the device of the present invention can be usedfor any task where precise, stable motion initiated and/or controlled bya human is required. The device can be modified to accommodate anyportion of a person's body that would be used to form such a precisefunction. In a preferred embodiment, the device is suitably designed fora person's hand. However, the device can be modified to accommodate aperson's foot or other appendage, for example, the arm of an amputee. Inaddition, the device can be modified to accommodate any type of tool.For example, the device can be used for microsurgery, wherein the deviceaccommodates a surgical tool such as a forceps or scalpel.

The device is particularly useful in reducing or eliminating the effectof a user's hand tremor on the function being performed. For example, aperson's heart beat can create unintentional motions of the person'shand and, therefore, also in a tool that is being held in the person'shand. Further, most individuals display some amount of tremor in theirhands that can be significantly larger than the motion due toheartbeats. A benefit of the device of the present invention is tosignificantly reduce such unintentional motion, and yet allow naturalcontrol of the translation of the hand within the travel range of themicromanipulator. An additional benefit of this device is that it allowsvery precise motion of the hand to be done very slowly. For example, infree hand motion, people often seek better precision in a task byperforming a motion quickly, but such quick motion has the disadvantageof preventing the person from perceiving the result of the motion whilethe motion is in progress. Using this device, the operator is able tomove both precisely and slowly, if desired.

Referring now to FIG. 1, an exemplary embodiment of the device 110 ofthe present invention is shown. Device 110 includes a base 120 and asensor assembly 130. In one embodiment, base 120 can be fastenedsecurely to the surface on which it rests. In another embodiment, base120 can include non-slip pads to prevent movement of the base withoutbeing fastened to the surface on which it rests. In yet anotherembodiment, base 120 is shaped and/or is sufficiently heavy to providestability, such that base 120 cannot slide on the surface on which itrests while in use. One end of sensor assembly 130 is mounted to base120 via a bracket 132. A grip 136 is connected to the other end of arm.Grip 136 can be adapted to hold a tool 119, for example a forceps, andcan also be adapted for a person's hand so that an operator cansimultaneously hold grip 136 and tool 119. Accordingly, the operator ofdevice 110 can use tool 119 to manipulate a sample 118 placed onpedestal 117.

The device 110 of the present invention is generally used as follows. Anoperator holds grip 136, wherein tool 119 is connected to grip 136 viatool support 134. Forces applied by the operator's hand through grip 136are transmitted to sensor assembly 130 (shown in detail in FIG. 2). Theother end of sensor assembly 130 is held fixed via a connection tobracket 132 which in turn is connected to base 120. The device furthercomprises a micromanipulator and also a microcontroller, i.e., amicroprocessor, which can both be located in base 120. Device 110provides sufficiently rigid support for the operator's hand so that theforce from unintentional motions of the hand is significantly reduced.Accordingly, grip 136, sensor assembly 130, bracket 132, and base 120each provide sufficient stiffness and rigidity to keep grip 136 and tool119 from moving in an unintentional or unguided way.

When the operator applies a force to grip 136, the force is transmittedto sensor assembly 130. Sensor assembly 130 transmits information aboutthe force to the microcontroller, which uses this information to provideinstructions to the micromanipulator. The micromanipulator can then movebracket 132 and thus the connected assembly, including sensor assembly130, grip 136, and tool 119, and may also send a signal back to themicrocontroller. Accordingly, sensor assembly 130 is designed to providea stabilizing counterforce to the operator's hand, and translate thehand, grip 136, and tool 119 in response to directive forces from thehand. The result is that device 110 dramatically reduces the speedand/or distance of the actual motion of the grip compared to therelative force applied by the operator. Accordingly, the operator hasdirect control over the movement of the grip and any tools associatedwith the grip, but the tool 119 and the operator's hand aresignificantly stabilized.

One advantage of the embodiment shown in FIG. 1, is that while tool 119is directly supported by the device providing for stability and highlycontrolled motion, tool 119 can also be operated directly by a person'shand. For example, a forceps can be opened and closed using finger orthumb pressure. Other variations of tool control are possible. Forexample, a small motor can be used to open and close the forceps, ortools other than forceps can be used and some of these can also have thepossibility for direct user control.

Typically, when the operator applies a force to grip 136 in a particulardirection, the programming of the microcontroller would respond to themeasured forces by sending a signal to the micromanipulator to move theassembly in this same direction as the applied force, with a speedproportional to the force applied by the operator. This proportionalcontrol can be adjusted using a gain factor that sets the constant ofproportionality for determining the speed from the applied force. In oneembodiment, the gain factor can be adjusted using a footpedal-controlled variable resistor, which is connected to themicrocontroller, allowing the operator to actively control theresponsiveness of the system. For example, the operator can set the gainto its highest value so the system moves quickly when far from theobject, and reduce the gain during delicate procedures. The operator canalso reduce the gain to zero so that the micromanipulator does not movesensor assembly in response to the applied forces. In one embodiment,there can still be some motion possible in the sensor assembly, due tothe flexibility of sensor subassemblies, and using the system in thisway can be useful for some tasks.

Referring now to FIG. 2, an exemplary embodiment of sensor assembly 130is shown. Sensor assembly 130 comprises three sensor subassemblies 142,144, and 146 that each respond to forces along a direction based ontheir respective orientation. Specifically, sensor subassembly 142responds to movement along the X-axis, sensor subassembly 144 respondsto movement along the Y-axis, and sensor subassembly 146 responds tomovement along the Z-axis.

Referring now to FIG. 3A, an exemplary embodiment of a sensorsubassembly, or force transducer, is shown. Sensor subassembly 146comprises a sensor 160 for measuring the relative motion between blocks156 and 158. In one embodiment, sensor 160 is a TRACKER™ sensor (NewScale Technologies, Inc.). Sensor 160 measures any motion that isperpendicular to the surface of one or more sheets 166. Blocks 156 and158 are similar in shape and size, and are held apart by sheets 166. Inthe exemplary embodiment shown, two sheets 166 are attached to oppositesides of blocks 156 and 158, wherein blocks 156 and 158 are spaced tocreate gap 159. The nearest faces of blocks 156 and 158 are held alignedand approximately parallel by sheets 166. In various embodiments, anynumber of sheets can be used to hold the blocks in alignment. Using morethan two sheets can enhance aspects of the performance of the sensorsubassembly, such as reduced rotation, and reduced translation in anon-preferred direction.

Sheets 166 are attached to blocks 156 and 158 via sheet fasteners 153.In one embodiment, as shown in FIG. 3A, each sheet fastener 153comprises a bar and two screws. However, each sheet can be connected tothe blocks by any fastening mechanism known to a person skilled in theart, for example, but not limited to, an adhesive or a clamp. In oneembodiment, the sheets and blocks can be a single structure, forexample, if the sheets and blocks for a single subassembly are producedby additive manufacturing techniques, i.e., 3D printing.

Sensor subassembly 146 further comprises a bridge 162 connected to block158, wherein bridge 162 also spans gap 159. Magnetic bar 164 isconnected to bridge 162, and is positioned such that it is suitablyaligned with sensor 160, but docs not contact sensor 160. Accordingly,magnetic bar 164 moves with block 158, while sensor 160 moves with block156. Therefore, the relative motion between blocks 156 and 158 can bemeasured by sensor 160. Thus, sensor subassembly 146 acts as a forcetransduction mechanism in that the amount of relative motion increaseswith the magnitude of an applied force, wherein sensor 160 measures thisrelative motion. The information related to the relative motion sensedby sensor 160 can then be transmitted to a microcontroller.

Referring again to FIG. 2, three sensor subassemblies 142, 144, and 146are shown connected together to form sensor assembly 130, wherein eachsubassembly can sense movement in a single direction, and wherein thethree sensor subassemblies are arranged to sense movement along allthree axes (X, Y, and Z). Specifically, sensor subassembly 142 connectsblocks 152 and 154 and senses motion along the X-axis; sensorsubassembly 144 connects blocks 154 and 156 and senses motion along theY-axis; and sensor subassembly 146 connects blocks 156 and 158 andsenses motion along the Z-axis. In such an embodiment, block 154 isL-shaped in order to allow for the sensing of movement along any of thethree axes.

As shown in FIG. 2, the individual sensor units can be connectedserially. That is, when a grip is attached to the a surface on block158, and the sensor is mounted to the micromanipulator at a surface onblock 152, a force applied at the grip in the X direction, that willprimarily activate the sensor subassembly at unit 142, must betransmitted through sensor subassembly units 144 and 146. The selectivemotion and response of these units allows them to act largelyindependently of each other.

Referring again to FIG. 1, in one embodiment, sensor assembly 130 can bepositioned such that block 152 is connected to bracket 132 and block 158is connected to grip 136.

That the subassemblies have a reduced rotational response to torques isalso particularly advantageous because, given the small distance scalesover which this device is designed to operate, and the comparativelylong lever arms of tool 119 and the length of sensor assembly 130, evenvery small rotations could result in significant motions of the toolnear sample 118. For example, if the operator applies a force to grip136 in order to cause sensor subassembly to move tool 119 a distance of20 microns toward sample 118 (just due to the flexion of the sensor, notthe motion of the micromanipulator), this force will also create atorque at all of the subassemblies within sensor assembly 130. If theresult of this torque were to produce even a very small rotation of,say, 0.01 degrees, the resulting motion through a 4 cm lever arm wouldbe approximately 7 microns, and could cause a motion of the tool in anunintended direction, which would make the system difficult to use.

One advantage of the device of the present invention is that each of thesensor subassemblies are relatively responsive to the component of theapplied force that is perpendicular to the sheets, but relativelyunresponsive to torques and components of the applied force that areorthogonal to the perpendicular direction. That is, the relative motionof two paired blocks, for example, blocks 156 and 158, is primarilyalong only a single direction, and there is very little rotation.

An advantage of the mechanism of the sensor subassemblies presented inFIGS. 2 and 3 is that they do not require any sliding components, suchas bearings or bushings. Such components can have mechanical play or astick-slip action that can easily produce undesired motion in thedevice.

The sensors of the present invention are used to measure the relativemotion between blocks, but in another embodiment the absolute positionof the blocks can also be measured. For example, a set of threeinductive position sensors can be affixed to rigid mechanical extensionsthat are affixed to bracket 132 (FIG. 1) so that they are held near thesides of sensor assembly 130, and positioned to detect motions in thethree orthogonal directions.

As would be understood by a person skilled in the art, the arrangementof sensor subassemblies in order to sense all three axes is not limitedto the embodiment shown in FIG. 2. For example, the location of sensorsubassembly 144 (Y-axis) can be switched with sensor subassembly 146(Z-axis). Further, in one embodiment, sensor assembly 130 can comprise atwo-axis sensor assembly instead of the three-axis assembly shown inFIG. 2, for example in applications requiring restriction to two-axismovement. Similarly, in another embodiment, a single axis assembly canbe used, wherein the sensor assembly is a single sensor subassembly.

The blocks of device of the present invention can comprise any shape,size, or composition, as would be understood by a person skilled in theart. In a preferred embodiment, the cross-sectional shape of the blocksis rectangular in shape, as shown in FIG. 2. However, the blocks canhave other cross-sectional shapes, such as, but not limited to aparallelogram, or a hexagon. Accordingly, the device of the presentinvention can comprise any number of sheets connecting the blocks,depending on the cross-sectional shape of the blocks, and/or the desiredstability and performance of the device.

Similarly, the blocks of the device of the present invention can besolid, hollow, or have openings or channels in the surface of theblocks. Further, the blocks can have varying dimensions, for example,the blocks can be wider or larger at the point where the sheets areconnected to the blocks compared to other portions of the block. Inaddition, the blocks can have rounded or beveled edges where the sheetsare attached to the blocks, for example to reduce the amount of localstress compared to sharp, right angle edges.

In one embodiment, the sensor subassembly comprises a sheet springmechanism, as shown in FIG. 3A. In another embodiment, the sensorsubassembly of the present invention can comprise a notch-type springflexure mechanism 200, as shown in FIG. 3B, which can also achieve thesame advantages of the sheet spring mechanism, and is assumed to bewithin the scope of this invention. Both mechanisms are known in the artand described in Smith and Chetwynd, Foundations of UltraprecisionMechanism Design, Vol. 2, 1992, Gordon and Breach Science Publishers,which is hereby incorporated by reference in its entirety. The blocks ofthe present invention can comprise any material, for example, but notlimited to aluminum, steel, or other metal, carbon fiber, or any type ofpolymer. In an exemplary embodiment, the dimensions of blocks 152, 156,and 158 are 0.75 inches on each side and comprise aluminum. The gapbetween each block is 0.2 inches. Each sheet is 0.01 inch thick andcomprises stainless steel. With these dimensions and TRACKER sensors,when the operator applies a comfortable amount of force typical fordelicate procedures, tool 119 will move in a range of about 0 to 500microns, depending on the amount of force applied by the operator.

The sheets of the present invention can be any shape, size, orcomposition, as would be understood by a person skilled in the art. Inone embodiment, the sheets are generally rectangular in shape and aresized to cover most or all of the width of the blocks of the presentinvention. In another embodiment, the sheets can be strips, i.e., thinrectangles than cover only a portion of the width of the blocks. In suchan embodiment, multiple sheets in the form of strips can be attached toa single face of a block. The sheets of the present invention aregenerally flexible to allow some movement, but stiff enough to providecounterforce to prevent significant movement of the blocks and stabilizetremor from the operator.

In various embodiments, the material properties and dimensions of thesheets and the size of the gap between blocks can be modified to adjustthe sensitivity and performance of the device of the present invention.Further, the sensitivity of the sensors in the sensor assembly is also afactor in determining the overall performance of the device. Thedimensions and material properties of the sheets and/or gap size aregenerally chosen so that an ergonomically reasonable amount of forceapplied by the operator's hand will result in a motion of the blocksthat is within the sensitivity of the sensor. For example, a smaller gapsize can provide a more selective response to the force in a directionperpendicular to the sheets, rejecting other forces and torques. In oneembodiment, very sensitive position sensors (e.g., capacitive orinductive sensors) can be used to enable the device to work at extremelyfine scales, especially when a smaller gap size and thicker sheets areused. For example, operators with significant hand tremor, might need astiffer device, which can be made by decreasing the gap size and/orincreasing the sheet thickness. For some uses, it may, for example, beadvantageous to reduce the gap size and also reduce the thickness of thesheets. In one embodiment, the sensor subassemblies can have differentcharacteristics. For example, a device that is stiffer along a singleaxis may be desired, wherein the gap size is smaller and/or the sheetthickness is larger for the sensor subassembly associated with movementalong that axis, compared to the gap size and/or sheet thickness of theother two sensor subassemblies.

The various components of the present invention can comprise a varietyof materials. For example, the blocks and bridge can be from a hardpolymer, a composite material, or a range of metals such as brass,titanium, or steel. The sheets of the present invention are generallymade from a range of materials, such as metal or polymer, so that thethin sheets are sufficiently flexible, yet strong enough to support theattached structures. However, the various components of the presentinvention can comprise any materials known to a skilled artisan, and arenot limited to the specific materials described herein.

In various embodiments, the device of the present invention comprises amicromanipulator. In one embodiment, the micromanipulator is a 100crsystem driven with the 421 DC motors, for example from Siskiyou DesignInc. In another embodiment, the micromanipulator can be a SutterInstruments MP-285 micromanipulator. However, the micromanipulator canbe any type of micromanipulator, as would be understood by a personskilled in the art. The micromanipulator is used to control some or allof the motion of grip 136. In one embodiment, the micromanipulator canmove the grip via direct contact with the grip. In another embodiment,the micromanipulator can move the grip via interaction with the sensorassembly, wherein the sensor assembly is connected to the grip.

In FIG. 1, sample 118 and pedestal 117 are fixed, and themicromanipulator of the present invention moves the sensor assembly 130and grip 136. In another embodiment, the sensor assembly 130 and grip136 can be held fixed, and pedestal 117 can be integrated with themicromanipulator, such that pedestal 117 is moved by themicromanipulator in response to forces applied to the sensor assembly130. This approach has certain advantages, such as the dynamic forces onthe micromanipulator are reduced and the tool remains in anapproximately fixed position, and therefore is easier to keep in withinthe focus of a microscope.

In various embodiments, the device of the present invention comprises amicroprocessor or microcontroller. The microprocessor can be anymicroprocessor suitable for processing data from the sensor assemblyalong with any other sensors or inputs from the device. In addition, themicroprocessor can be any microprocessor suitable for controlling themicromanipulator. In one embodiment, the microprocessor can be connectedto the other components of the device via wires. In another embodiment,the microprocessor can be connected to the other components wirelessly,for example via WiFi or Bluetooth.

The method and arrangement of wiring or connecting the variouselectrical components and mounting them will be well known to those withordinary skill in the electronic and mechanical arts. The wiring pathsare not shown in any of the figures nor are power supplies for any ofthe components. FIG. 4 shows signal inputs and outputs of themicrocontroller. The microcontroller receives information from thesensor assemblies, indicated as the X-, Y-, and Z-axis transducers inFIG. 4. The microcontroller may also receive other information. A gaincontrol can be adjusted by the operator and its state is communicated tothe microcontroller, and can, for example, be a potentiometer with adial or foot pedal that is controlled by the operator. A zero button isalso indicated in FIG. 4, and this button can be depressed by theoperator and its state read by the microcontroller. In addition, themotors of the micromanipulator or other sensors can provide informationto the microcontroller, such as travel range limits, or positionmeasurements, as is common for closed loop control of motor motion. Themicrocontroller also communicates with the micromanipulator to controlthe motion of micromanipulator, indicated in FIG. 4 as the outputs tothe X-, Y-, and Z-axis motor controls. The microcontroller also controlsfeedback to the user. It may drive a buzzer and a liquid crystal display(LCD), as indicated in FIG. 4, or other type of display, or it may alsogive feedback to the operator through controlling other indicators suchas light emitting diodes, or haptic technologies. It is also possible tohave the microcontroller communicate with a personal computer and usethis to provide the functionality of the buttons, displays, and buzzersthrough a graphical user interface running on the personal computer.Other operator controlled switches and settings for the microcontrollermay also be useful, such as an engage/disengage switch, that can disablethe motor drive functionality of the microcontroller; or a run/adjustswitch, to select between a normal use mode and a mode where theparameters to the device can be more conveniently adjusted, for example,where more information is displayed about the internal state of thedevice that may not be desired during normal use. A specific case forthe later example is that the TRACKER sensor used in the currentembodiment can provide detailed information that wouldn't normally beuseful while running, for example, information useful for positioningmagnet 164 relative to sensor 160.

In one embodiment, the device can be calibrated using a zero offsetbutton. To calibrate a zero offset the operator will typically avoidtouching the device while depressing the zero button. Once the zerobutton is depressed, the microcontroller will calculate an average ofthe transducer readings over a short time period. The microcontrollercan store this value and use it subsequently, for example, to subtractthis average from each of the ongoing transducer readings. In oneembodiment, if a tool is attached to the system and the device is zeroedwhen the operator is not touching the device, then once the operatordoes begin to use the device, only the additional forces supplied by theoperator will be used by the device to determine the motion. In anotherembodiment, the operator can zero the device while applying anapproximately constant force to the device. This approach can, forexample, allow for bi-directional control along any direction even withunidirectional forces, where the direction of the resulting motion willdepend on whether the force along any axis is greater or less than theinitial force applied. Zeroing can also help compensate for drift in thesensor readings or changes in static forces applied to sensor assembly,such as when tools are changed.

In one embodiment, the microcontroller can also provide visual andauditory feedback to the operator. In one embodiment, themicrocontroller can activate a buzzer (see FIG. 4) when excessivedeflection is measured by the transducers. In another embodiment, themicrocontroller can provide visual feedback to the user via displays orlights that can indicate various information, such as, but not limitedto: whether power is being supplied to the device, whether the systemhas been zero corrected, the zero corrected and uncorrected readingsfrom the three transducer assemblies, or values indicating the speed ofthe three axes of the micromanipulator.

In various embodiments, other operator input interfaces can be used,such as using voice commands to instruct the device to change gainsettings, or to zero the device.

A variety of algorithms can be used by the microcontroller to controlthe motion of the device. In one embodiment, the output of the sensorscan be scaled and multiplied by a gain, then applied to amicromanipulator moving in the same direction as the sensor. Additionalprocessing may be useful, such as, low-pass filtering to remove jittersfrom the operator or environment; or the operator can wear a sensor tomeasure heartbeat timing, since heartbeats can cause unintended handmotion, and this information can be factored into determining theresponse to signals from the transducers; or the output can compensatefor dynamics of the motor; etc. The device can be programmed to notdrive the micromanipulators for very small forces, which would, in somecircumstances, cause the device to be slightly less responsive. Themicrocontroller can also be programmed to respond to rapid changes inforce as reported by the transducers, or respond to an additional sensormeasurement, such as the force that the tool is applying to the object,or the temperature of the object, etc.

Although the sensor subassemblies respond primarily to forcesperpendicular to the sheets, they can also respond undesirably to forcesorthogonal to the perpendicular direction to the sheets. This mixing offorces can be corrected using standard mathematical techniques in theprogramming of the microcontroller. In addition, the axes of the sensorassembly and micromanipulator do not need to be aligned, as a simplecoordinate rotation can be performed using standard mathematicalmethods. Further, the sensor assembly units are not required to beorthogonal.

This device may also be useful for drilling through a tough materialdirectly abutted against a softer material, such as in the case ofdrilling though a cranium, with the brain located immediately below. Inthis situation, when drilling freehand, it is common to apply force tothe drill to promote movement through the tough material, and then failto remove this force quickly enough when entering the softer material.In this situation, the primary problem is that the speed through thematerial is determined by a combination of the force applied by theoperator of the drill and the type of material, so that when the softermaterial is entered, the drill moves very quickly. If, instead, thedevice of the current invention was used to move the drill through thematerial, even when controlled by an operator's hand, the maximum speedcan be limited to the speed range that would be useful when movingthrough the tougher material, so that the drill would not movesubstantially faster when moving through the softer material, and thusgive the operator more time to respond to entering the softer material.This technique would allow the operator to use the precision control ofthis device for accurate positioning and control of the drill, as wellas allow drilling with reduced penetration below the tougher material.For such applications, it may in some circumstances be advantageous touse a combination of parameters for gap 159 and the thickness of sheets166 so that the force on the drill required to drill through the toughermaterial does not flex the sheets more than the penetration toleranceinto the softer material, since once the drill penetrates through theharder material, and therefore meets less resistance force, it will moveto increase the flexion of the sheets and penetrate this distance intothe softer material.

An alternative method for using this device to drill through a toughmaterial directly abutted against a softer material, is to use sensorassembly 130 as a force sensor to measure the resistance to forwardmotion, as an aid in determining whether the drill has penetrated theharder material. In the normal mode, the device uses forces from theoperator's hand to guide the motion of the tool. This mode can be used,for example, when a small drill, such as a dental drill, is being usedfor tool 119, and the tip of the drill can be placed directly above thearea to be drilled. At this point, the operator can release their handfrom the grip and indicate to the microcontroller, for example, bypushing a button, that the drill was in place. With the operator's handremoved from the grip, the primary changes in the force applied to thesensor will be due to changes in the forces on the drill, and, in thisway, the sensor can be used to sense the forces on the drill. If themicromanipulators advance the drill through the bone at approximatelyconstant speed, the resistance to forward motion will change betweenwhen the drill is advancing through the bone and when it penetratesthrough to the other side of the bone. This change in force can then beused as a cue to the microcontroller to stop the forward motion of thedrill, and, optionally, retract it from the hole. The deflection of theforce sensor can also be used to control the speed of motion though thematerial, for example, if the resistance force to forward motion becametoo large, the speed of advancement can be reduced. An alternativemethod for testing for penetration though the bone is to observe thechange in force on a non-spinning drill by using the following cycle:the drill can be turned on to full speed and advanced a small distancethrough the material; then the drill can be turned off or slowed, andwhile in this state, the drill can be advanced slightly further to probethe resistance of the material (for example, 20 microns); whetherpenetration has occurred can be determined by observing the resistanceof the material, and if penetration is not observed, the cycle can berepeated. This method can be useful in cases where the change in forceon a drill spinning at constant speed was insufficient to determinepenetration. An advantage of using this device for this application isthat it can be guided into position using the hand-guided accuracyavailable with this device, and the grip can then be released and thedrilling process started, all very quickly and easily.

In one embodiment, the position or movement of the micromanipulator ortool 119 can be used by the microcontroller, and this would allow formany options for the device. (This can be done, for example, by using arepeatable motor drive, or by using encoders on the micromanipulator—apossible communication channel is shown as dashed lines in FIG. 4, orfor optical measurement, of the position of the tool tip). For example,the motion of tool 119 can be restricted to have reduced dimensionality,such as moving only in a plane or line; or boundaries can be put on themotion, for example, to prevent damage to nearby equipment, like amicroscope lens. Furthermore, the motion can be guided by input from theoperator referencing the sample 118: for example, the operator can guidetool 119 to two different points, and press a button at each point toindicate to the microcontroller that the point is selected, and then themicrocontroller can restrict the motion of the micromanipulator to onlyallow the tool to move along a line through these points. Or, this canbe externally referenced, for example, if the microscope that theoperator was using (not shown) was equipped with an encoder on the focusadjustment, the operator can focus the microscope on the tool and thenrefocus on the object, the microcontroller can record this difference infocus locations, and then automatically move the tool to be close to theobject (this process is often difficult for beginners).

Another application for this device, in which the microcontroller usesinformation about the position of the micromanipulator or tool, is indrilling through a surface in a pattern of small holes. For example, iftool 119 is a small drill that can be used to cut a hole larger than thediameter of the drill bit into bone, as is commonly done to access partsof the mouse brain in in vivo preparations. Here, once the mouse craniumis exposed, the operator can guide the drill point to touch threelocations on the cranium that lie on the perimeter of the desired hole,and the microcontroller can read the positions of these three points.Software can use the three points to determine the desired circle(including the orientation of the plane in which the circle lies). Theoperator can then remove his hand from the device and the drilling ofeach hole around the pattern can proceed, and each hole can be drilledwith the device by sensing of forces on the drill to stop penetrationonce beyond the cranium thickness (as described above). Many holes canbe drilled around the perimeter of the circle, each one startingslightly above the circle, and then the device can move quickly untilthe drill tip contacted the cranium (as determined by the force of thedrill contacting the cranium); if not already spinning, the drill canstart spinning once contact is made; the drill can then advance throughthe bone until the force changes on the sensor indicated that the drillwas through the bone; the drill can then be retracted back through thehole; and advanced to the next hole. Similarly, holes of arbitraryshapes can be created by hand-guiding a trace of the desired holeperimeter on the surface of the cranium, these positions can be storedin the microcontroller, and the grip released to automatically drill therequired pattern to create the traced hole. An alternate approach todrilling a sequence of small holes around the perimeter is to move thecutter along the perimeter, possibly making multiple passes around theperimeter, while also monitoring the resistance force in the directionthat would indicate breakthrough to the softer material, in order toavoid cutting into the softer material, and simultaneously measuringforce along the perimeter of the cut to control cut speed and force. Anadvantage of this device is that it encompasses a system to preciselyposition the drill, and then drill the hole; and for a pattern of holes,such as required to cut the perimeter of a larger hole, the shape of thelarger hole can be directly indicated with this device, and thenrequired pattern of holes can be drilled to release the larger hole.

The present invention can include other components. For example,rotating joints, sensors to indicate joint angle, and a spring to keepthe structure rigid enough to provide stability to the operator can beused. A motion stop mechanism can be added to the sensor subassembliesto limit extreme and/or possibly damaging deflections. For example,referring to FIG. 3A, the motion stop mechanism can comprise a rodinserted into openings in blocks 156 and 158, wherein the rod spans gap159. The openings can be sized to be slightly larger than the width ofthe rod. An undesirably large movement would force the rod to contactthe side of one of the openings, thereby limiting the motion of theblocks. The device may also comprise strain gauges attached, forexample, to the sheets of the sensor assembly.

Other mechanisms of a motor driven stabilizing sensor are also possible,such as using long rigid rods with the tool and grip assembly at one endand a semi-rigid mounting structure at the other. For example, a pieceof straight tubing can be attached to one of the blocks of a singlesensor unit and mounted so that the axis of the rod is perpendicular tothe sheets, and a tool holder can be attached to the other end of therod. Strain gauges can be attached to the rod to measure its bending. Inthis configuration, the strain gauges can measure forces in the twodirections perpendicular to the axis of the rod and the sensor unit canmeasure forces parallel to the axis of the rod, so, effectively, theflexing of the rod and the measurements of this flexing by the straingauges can eliminate the need for two of the three sensor units. In thisconfiguration, the rod can also twist around its axis due to the appliedtorques, and dimensions should be chosen so to keep this within anacceptable range for each application.

In various embodiments, the grip of the present invention can compriseadditional components, and can be made in a wide variety of designs andform factors. Referring to again to FIG. 1, many different grips andtool mounting systems are possible with this device, and grip 136 andtool assembly 134 shows a particular embodiment to demonstrate apossible use case for this device. Grip 136 forms a grip that is heldbetween two of the operator's fingers. A truncated sphere that isattractive to magnets and is mounted to a platform and magnetic ring isplaced on the sphere. Tool 119 has a sufficient degree of attraction tothe magnet that it is conveniently held in place on the magnetic ring,and may also be opened and closed by the operator's thumb. The magneticring can be repositioned on the sphere to change the angle of the tool.An alternate arrangement is to make grip 136 so that it can becomfortably held between the thumb and middle finger, and tool 119 canbe operated by the index linger. An additional alternate arrangement isfor the operator to hold tool 119 between the thumb and index finger andfor tool 119 not to be in contact with other parts of grip 136 or toolassembly 134. Many other designs for the grip and tool holder arepossible, having different ergonomics, holding different tools, andproviding different degrees of freedom.

In another embodiment, grip 136 comprises a fixed point tool holderdesigned to allow a rotation of the tool while keeping a point fixed inrelation to the tool, also fixed in space. Once rotated, the holder willalso keep the tool stable enough to do precision work, even while theoperator's hand is on the grip. A schematic diagram of such anembodiment is shown in FIG. 5. Grip 136 comprises three generalcomponents that further include various subcomponents. The generalcomponents are: a rotational housing 10. which has a rigid mount point22, to a support 14; a tube 12 which extends from rotational housing 10;and a combined grip 34 and tool holder 32 (see FIG. 6) which attaches totube 12. Rotational housing 10 is fixed in relation to support 14, buthas an internal locking mechanism which can be remotely controlled bythe operator to allow tube 12 to rotate or be locked rigidly in place.

Referring again to FIG. 5, grip 136 is designed to be mounted to asupport, here shown as support 14. In one embodiment, support 14 can beblock 158 in FIG. 2, i.e., the tool holder and rotational devicedescribed in this section can be adapted or connected to sensor assembly130 described previously herein. In another example, sensor assembly 130can be located in base 120, or can be mounted to some other structure,wherein the embodiment of grip 136 shown in FIG. 5 is mechanicallyconnected to sensor assembly 130. In such an example, grip 136 can beconnected to block 158 of sensor assembly 130 via mount point 22.However, in various embodiments, support 14 can be any structure that isfurther connected to sensor assembly 130 and can communicate directiveforce to sensor assembly 130.

Referring to both FIGS. 5 and 6, the operator's hand 18, holds the grip34. From this grip 34 the operator can operate tool 28 (here illustratedas forceps, but any of a range of tools can be used), and also, whentube 12 is locked in place, provide directive force on grip 34 which ismechanically transmitted through grip 34, to tube 12, to rotationalhousing 10, to support 14. Support 14 can sense the directive force andmove in a direction consistent with the directive force. Pedestal 17holds object 16, and these are not part of the invention but shown onlyfor illustration. This explanation is not intended to limit the scope ofuse for this invention, but provide a usage example showing acircumstance in which it would be useful to have a device, such as thisone, which allows rotation of a tool, but not direct translation; thatis, this device allows for rotation of a tool, whereas the supportallows for translation.

The goals of this device are as follows: 1) allow tool 28 to be rotatedabout one or more axes; 2) during rotation, keep tool tip 24 so that ithas very little translation relative to support 14; 3) after rotation,allow all parts inclusively between grip 34 and mount point 22 to belocked sufficiently rigidly in position so that the operator's hand doesnot create excessive motion of tool tip 24 due to independent motion ofthese components; 4) allow tool holder 32 to rotate under forces applieddirectly to it or to tool 28, but configured so that forces applied togrip 34 do not cause rotation of tool holder 32. An example of severalpossible rotations are shown in FIG. 6, where for each rotation, tooltip 24 remains in approximately the same position relative to rotationalhousing 10. From the starting position shown in FIG. 6A, tool holder 32rotates relative to grip 34, therefore also moving attached tool 28, togive the view in FIG. 6B; and in FIG. 6C, tube 12 rotates relative torotational housing 10, therefore also moving grip 34 and tool holder 32.Translation of tool tip 24 can be reduced during rotation of the tool iftool tip 24 is close to the axis of rotation, whether for one or moreaxes. A feature of the device and its variations discussed here is toalign tool tip 24 so it is on or near the axes of rotation.

FIG. 7 the shows a detailed view of rotational housing 10 and tube 12,with a broken-out section. All structures in FIG. 7 are made out ofmetal, such as aluminum, brass, or stainless steel, except where noted.Part 48 is a standard pneumatic piston (purchased from Mac Corporation)and is only shown here in detail sufficient to explain its usage in thisdevice. Annulus 48A of pneumatic piston 48 is bolted to plate 42,creating a pneumatic seal. Hole 46 feeds through to pressurize the areaunder piston 48B, forcing piston 48B in a direction away from plate 42.Hole 46 is connected to a source of operator controlled pressured gas,and is connected using standard techniques. The pressurized gas forcespiston 48B into disk 52, which is a rigid disk to aid in distributingthe pressure onto disk 54. Disk 54 is an elastic material, with a pieceof stiff rubber, or, for example, a spring washer. Disk 54 aids inkeeping the force between the plates equal to the force from thepressurized gas on the piston. Disk 56 is a low friction material thatcan slip against annulus 58, allowing annulus 58 to rotate more easily.Plug 64 has a threaded hole 68 to receive screw 66, and plug 64 is alsorigidly attached to tube 12A (the first segment of tube 12); in thepresent embodiment plug 64 is made from brass and is silver solderedinto tubing 12A, which is made from stainless steel. Annulus 58 alsopresses against bushing 60, and bushing 60 presses against housing 44.Housing 44 is rigidly bolted to plate 42; plate 42 is rigidly bolted toplate 40, and plate 40 is integral with mounting point 22. Disks 52, 54,and 56 are not attached to anything but are only held in place by theforce from piston 48B. Retaining ring 50 encircles these three disks tokeep them aligned when the piston is retracted. In the presentembodiment, tube segments 12A, 12B, and 12C are made from stainlesssteel and are welded together to form tube 12.

Rotational housing 10 and tubing 12 can be used in the following way.Bolt 66 forces annulus 58 against plug 64, which therefore makes theassembly of parts 12, 64, 58, and 66, form a rigid body. Removing bolt66 from plug 64 allows tube 12A to be pulled out of bushing 60, andtherefore tube 12 can be exchanged. When fully assembled, as shown inFIG. 7, force from piston 48B is transmitted through the series of disksto force annulus 58 against the flat surface 72 bushing 60, and thenbushing 60 against housing 44. The pressure on piston 48B can be variedto allow the rod to rotate smoothly at lower pressures, or lock it inplace when higher gas pressures are applied. When the gas pressure onpiston 48B is low enough to allow the piston to rotate, tube 12 can alsotilt when sufficient force is applied by the operator, but this tilt isreduced by the close fit of the bored surface 70 of bushing 60. As thegas pressure becomes higher, the force stopping tube 12 from tiltingcomes from the pressure against flat surface 72 of bushing 60. Thisfeature of this device allows for more stability in tool tip 24 than canbe had by the fit of the bushing alone. Overall, rotational housing 10allows tube 12 to be rotated with an amount of friction that can be setby the operator, only a small amount of tilt of tube 12 during rotationdue the close fit of the bushing, and higher stability of tube 12 in thelocked position than can easily be attained by the bushing fit alone.

An alternative embodiment of rotational housing 10 is to have a slot ona side of housing 44 so that subassemblies comprising tube 12, bushing60, plug 64, annulus 58, and bolt 66, can be easily exchanged throughthe side slot.

FIG. 8 shows grip and tool holder 20, where its two main components,grip 34 and tool holder 32, are separated. These are intended to beeasily separated and reassembled together. To reassemble, rod 80 is setinto opening 84, and to disassemble, they are simply pulled apart. Rod80 is made of a material that will be attracted to magnets, and thereare several magnets in grip 34, where in this view, only magnet 86 isvisible. Magnet 86 is inset into a receiving cup so that when assembled,it is held close, but so that it does not touch rod 80. Other magnetsare inserted into channels 88 which run the length of grip 34. Tool 28is held onto platform 78 with clips 82, and adjust the position of tool28 on platform 78 can be useful during alignment. Platform 78 issupported above rod 80 by a set of evenly spaced parallel plates 76.When assembled, the tool holder's parallel plates 76 interleave with thegrip's parallel plates 74, and are designed so that when assembled, toolholder 32 can freely rotate about the axis of rod 80 by more than 90degrees. The interleaved nature of plates 74 and 76 provides acomfortable interface for the operator's hand 18, since the finger canhold these structures at any angle of rotation.

FIG. 9 shows another view of grip 34, and shows more details of the seatfor rod 80. Patch 100 shows the other side of the hole for magnet 86.Two other magnets, 104 and 106, are located just below surface 102.Surface 102 is flat except for a shallow recess 94, which runs almostthe full length of channel 84 but stops just before the ends, leavingtwo small ridges 90 and 92 at either end of the channel. These ridgessupport the ends of rod 80. Grip 34 is bilaterally symmetric, wheresurface 108 is the mirror image of surface 102, and all of features 90,104, 94, 102, 92, and 106 are duplicated in mirror symmetry. In thepresent embodiment, grip 34 is manufactured from plastic by a 3D printerwith magnets inserted after printing.

FIG. 10 shows a view of tool holder 32 without tool 28. Shim 180 willlift tool 28 further off the end of platform 78. This is a usefuladjustment as it tips tool tip 24 forward, which can be useful to setthe distance of tool tip 24 from the rotational axis of rod 80. Otheradjustment mechanisms are clearly possible, such as set screws to lift aportion of tool 28. Furthermore, the angle of platform 78 can bedifferent for different tool holders, tools, and operator preferences.

A feature of the design of the grip 34 and tool holder 32 is that tooltip 24 can be aligned so that it is located on or near the axis of rod80. When seated in grip 34, rod 80 will be held so that it can rotateabout its axis, and will be held in place by magnets, 86, 104, 106, andthe symmetric pair of magnets to 104 and 106. The force of these magnetscan be selected so that tool holder 32 can be easily rotated with thefingers or thumb but stays in place when not intentionally rotated.

Grip 34 is assembled to tube 12 by inserting tube segment 12C into hole98, and a nut and bolt cart be used with flange 96 to firmly secure thisattachment. The assembled arrangement is shown in FIG. 11 which alsoshows the resulting axes of rotation, axis 190 for rotation about rod 80and axis 192 for rotation of the tubing in rotational housing 10, whichrotates with the cylindrical axis of tube segment 12A. Combining theserotations can give the configurations shown in FIG. 6, and many more.For tool tip 24 to not translate during these rotations, tool tip 24must be on both axes. This can be adjusted as already described. Anadditional adjustment is possible if axis 192 is not parallel to thecylindrical axis of tube segment 12C, so it is useful to have these twoaxis non-parallel, since in this case, the distance from tool tip 24will be changed as the grip 34 is slid a bit further on or off tubesegment 12C.

An advantage of current design is that the grip 34 and tool holder 32allow for very precise rotational control of tool tip 24. Effectively,the operator can gently push the tool holder 32 or tool 28 over anapproximate 0.75 inches of travel to cause a 90 degree rotation of tool28 (and tool tip 24). This is generally found to be more controlled andsmooth than making a similar rotation free hand.

Another advantage of the current design is that translation of the toolcan be directed independently from rotation of the tool. Thisindependence is implemented in several ways. In normal usage,translational directive force is applied to grip 34. This force will notcause rotation about axis 190 because it results in no net torque aboutthis axis, so it does not cause tool holder 32 or tool 28 to rotate.Directive translational forces applied to grip 34 will create a nettorque about axis 192, but when rotation of tube 12 is locked bystructure 10, no rotation will result. Combining these two approachessignificantly decouples directive translational forces from causingrotations.

For performing rotations when the tool tip (or other parts of thedevice) is near critical areas, it is possible to translate the tool soit is sufficiently clear of the sample, rotate the tool, and return thetool tip to its original position close to the sample. This is sometimesnecessary since although this system is designed so that directivetranslational forces lead to a reduced level of unwanted rotations,forces directed at causing a rotation, either of about axis 192 or aboutaxis 190, may result in translational forces acting on the sensor 130,and even when the gain is set to zero so the micromanipulators do notmove, this can result in some translation of the tool due to flexion ofthe sensor assembly 130. This is typically negligible for rotation aboutaxis 190, but can be more significant for rotation about axis 192, wherethe amount of resulting translational motion depends on details of theparticular embodiment, such as flexion of the sheets 166 and fictionbetween the moving elements.

An additional possibility for grip 34 and tool holder 32 is for tool tip24 to be intentionally unaligned with the rotational axis of rod 80.Specifically, many suture needles approximately form an arc of a circle,call this circle C. If the alignment of tool tip 24 were adjusted sothat when tool 28 was holding a suture needle, the cylindrical axis ofrod 80, was approximately passing through the center of circle C, andperpendicular to plane of circle C, and so that the arc of the sutureneedle was coincident with circle C, then as tool 28 was rotated in grip34, then the suture needle will follow through a single path, and, inparticular, through the hole in the tissue created by the tip of theneedle, and this would be beneficial in various circumstances.

Tube 12 is composed of sections 12A, 12B, and 12C. The particular shapeof this can be varied and is primarily designed around comfort for theoperator. The number of segments is variable, though at least two arerequired: one (12A) to establish the axis and the other to move theconnection point for grip 34 away from the axis of 12A. Many moresegments and bends can be included.

Other configurations of this design are possible. For example, thesystem can be designed around using an electromagnet instead ofpneumatic piston 48. The basic premise of the tool holder is for it torotate around a specific axis, such that the tip of the tool is alignedto be on, or near, said axis, and this feature can also be implementedin a variety of ways. The device can also include a semicircular track,where a grip or extended tool holder were constrained to remain in thistrack, thus establishing an axis where the tool tip to be located. Theseother approaches are considered to be within the scope of thisinvention.

The device of the present invention has many advantages over devicesknown in the art. One advantage of the device of the present inventionis that controlled motion that is more precise than the accuracy of thesensors is possible, depending on the chosen parameters of theconstruction and the operator using the device. For instance, when thesensor assembly 130 is built to be very stiff, for example, by makingthe sheets thick, or the gap size small, so that a large force appliedby the operator just reaches the threshold to produce a non-zero readingfrom sensor 160. In this case, smaller forces applied by the operatorwill still cause motion, and, for example, move a tool due to theflexion of the sheets, but these motions will be smaller than theprecision of sensor 160, so the motors will not be engaged. In this way,it can be possible to achieve finer motion control than would normallybe allowed by the precision of sensor 160. In a more typical use case,the stiffness of the system would be chosen so that a small, rather thanlarge, force from the operator would be required to reach the thresholdof the sensor, but yet even smaller forces would still produce motiondue to flexion that would be bellow the threshold of the sensor.Furthermore, this motion can be very natural for the user, in that whenforces below the threshold level of sensor are applied, the support andtool will move a small amount due to flexion of the sheets, and largerforces will include a generally larger displacement due to flexionsheets, plus motion due to movements of the micromanipulators, making itpossible to achieve a continuous, smooth, and natural-feeling userexperience. In addition, the motion due to flexion of the sheets isimmediate, responsive, and has a natural feel, with no time delay, bothin the cases where the motors are engaged, and when they are not, andthis adds significantly to the responsiveness and intuitive feel of thedevice.

Another advantage of the device of the present invention is forprecision motion control, where because the operator's hand isstabilized, the device requires less, and possibly no, algorithmicmanipulation of the measured forces from the operator in order to reduceundesired motion. That is, an alternate approach for using hand motionto guide precision robotic systems is to apply algorithms to free handmotion that, for example, scale or filter the measured motion in orderto reduce the unwanted motion. In some situations, this scaling and/orfiltering can have unwanted effects.

Another advantage of the device of the current invention is that whenthe rotation of tube 12 is locked, the device has no moving parts, andin particular no rotating parts, between the mount point 22 and grip 34.Forces are applied at grip 34 and any moving parts between grip 34 andmicromanipulators 120 are a potential source of mechanical play that canreduce overall stability. In particular, since the distance frommicromanipulators 120 and tool tip 24 can be many centimeters, thisdistance can be thousands of times larger than the acceptable error inthe position of the tool tip, and can function as a lever-arm throughwhich even small amounts of undesired rotation can act to create largemotions of the tool tip. In practice, this device allows for easy andprecise positioning and control of tools to accuracies below 10 microns,which is more precise than other devices by approximately a factor often.

Another advantage of the device of the current invention is that itreduces control difficulties that can be caused by rotational degrees offreedom. These difficulties arise because, for very precise motions, thetool length can be thousands of times the acceptable error in theposition of the tool tip, which leads to rotations being deleterious andhard to control. An example, for illustration purposes, is to consider a90 degree rotation of a 10 cm tool, where the tip is required to staywithin a 15 micron tolerance, and no restrictions are applied to theangles or positions of the tool. Such a rotation would require that theend opposite the tip move through an approximately 15 cm arc, whichimplies that the relative motions of the opposite ends of the tool needto be controlled with relative motion ratio of approximately 10,000to 1. Even with the aid of a device to steady, filter, and/or scale handmotions, as long as generalized rotations (i.e., rotations about anyaxis) and translations of the tool are allowed, the geometricalrequirements for this motion can make such generalized tool motionsextremely hard for an operator to control; for example, even scalinghand motion by a factor of 100 would still require a precision of 100 to1 for the geometry of this example. The device described here reducesthese control difficulties by ensuring that translational directiveforces do not cause unrestricted rotations. This is done using multiplemethods. One method used by this device for reducingcontrol-difficulties due to rotation is that the tool tip can bepositioned so that it is at or near to the mechanically determined axesof rotation, which reduces translation of the tool tip during rotation(compared to a more general rotation). Another method is that, aspreviously described, translation of the tool can be directedindependently from rotation of the tool, so that the control oftranslation of the tool is largely decoupled from rotation of the tool.For example, the device can be conveniently used without significantrotation of the tool; and for rotations in critical locations, the toolcan be translated sufficiently far away from the critical region toaccount for any translations that may occur during rotation, therotation can be applied, and the tool can be translated back to thecritical location.

These two methods for coping with inherent difficulties of generalizedrotational control on precision hand-guided movements are presented forthe device of the current invention, but their application to otherdevices is also considered to be within the scope of this invention. Forexample, other surgical robots that use hand guided motion control canhave a “microsurgical mode”, or be designed strictly for microsurgery,where: 1) rotations are only allowed about a specific axis or point; 2)translation and rotation are controlled independently. For item 1, therotation can be established about any fixed point or axis; this fixedpoint or axis can be established even if there is no mechanicalcomponent aligned with it, but instead, a virtual fixed point or axiscan be used that is implemented through the combined controlled motionof multiple components; commonly, the fixed point or axis of rotationwill be close to the tool tip, which is commonly close to the mostcritical part of the object, but this is not a requirement, and thescope of this invention is not limited to this choice; the fixed pointor axis of rotation can be selected by the user and changed at any time,and can, for example, be marked onto a tool, where the position of thesemarkings was also included in the algorithm of the controllingprocessor, in order to establish this as the fixed point or axis. Foritem 2: the goal of independent control is to have directive motions forrotational control so that they correspond only to the angle ofrotation, either in one dimension, or two, but not direct translation ofthe fixed point or axis of rotation, and to have motions that directtranslation correspond to pure translating motion in space withoutdirecting rotation; this can be implemented by temporally switchingbetween rotational and translational control, so that directive controlfor only one of either rotation or translation is active at the sametime, or, for example, by having different parts of the body controltranslation and rotation, for example, when translation is controlled byhand motion, rotation can be controlled by, for example, motion of afinger, foot, or hand different from the one directing rotation.

The present invention also relates to methods for controlling a tool orstabilizing the motion of a tool. In one embodiment, the method of thepresent invention comprises the steps of: sensing a force applied to agrip via a sensor assembly, wherein the grip is associated with a tool,sending an input signal to a microprocessor indicative of the appliedforce, sending an output signal from the microprocessor to amicromanipulator, wherein the output signal directs the micromanipulatorto apply movement to the grip in the direction of the applied force. Inone embodiment, the tool associated with the grip is selected from thegroup consisting of a forceps, scalpel, needle, and drill. In anotherembodiment, the output signal is produced by applying a gain to theinput signal. In yet another embodiment, the micromanipulator appliesmovement to the grip via the sensor assembly.

The disclosures of each and every patent, patent application, andpublication cited herein are hereby incorporated herein by reference intheir entirety. While this invention has been disclosed with referenceto specific embodiments, it is apparent that other embodiments andvariations of this invention may be devised by others skilled in the artwithout departing from the true spirit and scope of the invention. Theappended claims are intended to be construed to include all suchembodiments and equivalent variations.

1. A device for reducing tremor in a tool, comprising: a grip suitablefor engaging a tool, a sensor assembly connected to the grip, amicromanipulator associated with the grip, and at least onemicroprocessor operatively connected with the micromanipulator and thesensor assembly, wherein when a force is applied to the grip, the sensorassembly sends an input signal to the microprocessor indicative of theapplied force, upon receiving the input signal, the microprocessor sendsan output signal to the micromanipulator directing the micromanipulatorto apply movement to the grip in the direction of the applied force.2.-23. (canceled)
 24. The device of claim 1, wherein the grip comprisesa first portion, and a second portion configured to hold the tool and torotate relative to the first portion; wherein the first portion isconfigured to allow a user to apply forces to the first portion withoutcausing the second portion to rotate relative to the first portion. 25.The device of claim 24, wherein the second portion is configured so thatthe rotation of the second portion relative to the first portion has afixed point on or near the tip of the tool.
 26. The device of claim 24,wherein the grip is configured so that the second portion can be rotatedwithout transferring the external force to the flexible sensor assembly.27. The device of claim 25, wherein: the first portion of the gripcomprises a body having substantially cylindrical member; and the secondportion of the grip comprises a body comprising a channel to hold thesubstantially cylindrical member, wherein the body of the second portionis configured to retain the substantially cylindrical portion in stablecontact with the channel.